-<b>Quadrangle parameters</b> is a general hypothesis for
-Quadrangle (Mapping). This hypothesis gives a possibility
-of using Quadrangle (Mapping) mechanism for faces built on 3 edges.
-The hypothesis requires some vertex to be selected from the face; this vertex will be
-used as degenerated edge. The resulting mesh will include several triangles near this
-vertex. Hypothesis construction and resulting mesh is displayed at the following figures:
+<b>Quadrangle parameters</b> is a hypothesis for
+Quadrangle (Mapping), which allows using this algorithm for meshing of
+triangular faces.In this case it is necessary to select the <b>Base vertex</b>
+used as a degenerated edge.
+
+\image html hypo_quad_params_1.png "A face built from 3 edges"
+
+\image html hypo_quad_params_res.png "The resulting mesh"
+
+This hypothesis can be also used to mesh a segment of a circular face.
+Please, consider that there is a limitation on the selectiion of the degenerated
+vertex for the faces built with the angle > 180 degrees (see the picture).
+
+\image html hypo_quad_params_2.png "3/4 of a circular face"